* Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
> Merge commit 26d05b368a5c0 ("Merge branch 'kvm-async-pf-int' into HEAD")
> tried to adapt the new interrupt based async PF mechanism to the newly
> introduced IDTENTRY magic but unfortunately it missed the fact that
> DEFINE_IDTENTRY_SYSVEC() doesn't call ack_APIC_irq() on its own and
> all DEFINE_IDTENTRY_SYSVEC() users have to call it manually.
>
> As the result all multi-CPU KVM guest hang on boot when
> KVM_FEATURE_ASYNC_PF_INT is present. The breakage went unnoticed because no
> KVM userspace (e.g. QEMU) currently set it (and thus async PF mechanism
> is currently disabled) but we're about to change that.
>
> Fixes: 26d05b368a5c0 ("Merge branch 'kvm-async-pf-int' into HEAD")
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
This also fixes a kvmtool regression, but interestingly it does not set
KVM_FEATURE_ASYNC_PF_INT either AFAICS:
kepler:~/kvmtool.git> git grep KVM_FEATURE_ASYNC_PF_INT
kepler:~/kvmtool.git>
kepler:~/kvmtool.git> grep url .git/config
url = https://git.kernel.org/pub/scm/linux/kernel/git/will/kvmtool.git
So either I missed the flag-setting in the kvmtools.git source, or maybe
there's some other way to trigger this bug?
Anyway, please handle this as a v5.9 regression:
Tested-by: Ingo Molnar <mingo@xxxxxxxxxx>
Thanks,
Ingo
